Paper Title
Experimental Investigation and Numerical Simulation of Salt Irrigation Water Effects on the Unsaturated Soil Columns

Study of solute movement and salt accumulation in the soils has been interested by researchers in the recent decades. A proper understanding of these phenomena can improve the strategies related to application of saline irrigation water and salts leaching practices. Several approaches have been used for simulation of solute movement through soil profile. In this research HYDRUS-2D software was used for simulation of irrigation water salt movement and distribution in 36 soil columns included 3 soil textures (light, medium and heavy textures), 4 salinity levels (0.09, 4, 8 and 12 ds/ m) and 3 replications. Water applications were done for a 40 days period and salt distributions were measured in 3 depths along the soil columns at the end of this period. Consequently, the same conditions were defined for HYDRUS and the accuracy of this software in the simulation of salt distribution was investigated. Comparisons between observed and simulated data clarified that HYDRUS have satisfactory accuracy in the simulation of salt distribution in unsaturated soils. However, HYDRUS has better performance in the heavy and medium soil textures with respective RMSE values of 0.14 and 0.13 gr l-1 in comparison with light texture soil with RMSE value of 0.25 gr l-1. Moreover, the result showed that by increasing solute concentration, the accuracy of HYDRUS decreases. Keywords - HYDRUS-2D, Salt movement, Simulation, Soil columns.